Engines, including diesel engines, gasoline engines, gaseous fuel powered engines, and other engines known in the art exhaust a complex mixture of air pollutants. These air pollutants include solid material known as particulate matter or soot. Due to increased attention on the environment, exhaust emission standards have become more stringent and the amount of particulate matter emitted from an engine is regulated depending on the type of engine, size of engine, and/or class of engine.
One method implemented by engine manufacturers to comply with the regulation of particulate matter exhausted to the environment has been to remove the particulate matter from the exhaust flow of an engine with a device called a particulate trap. A particulate trap is a filter designed to trap particulate matter and typically consists of a wire mesh or ceramic honeycomb medium. However, the use of the particulate trap for extended periods may cause the particulate matter to build up in the medium, thereby reducing the functionality of the filter and subsequent engine performance.
The collected particulate matter may be removed from the filter through a process called regeneration. To initiate regeneration of the filter, the temperature of the particulate matter entrained within the filter must be elevated to a combustion threshold, at which the particulate matter is burned away. One way to elevate the temperature of the particulate matter is to inject fuel into the exhaust flow of the engine and ignite the injected fuel. During the regeneration event, fuel may flow through a supply circuit to the injection nozzle to support combustion of the particulate matter.
After the regeneration event, the supply of fuel is shut off. However, some fuel may remain in the fuel supply circuit and the injection nozzle. This remaining fuel, when subjected to the harsh conditions of the exhaust stream may coke or be partially burned, leaving behind a solid residue that can restrict or even block the injection nozzle and passages of the supply circuit. For this reason, it may be necessary to cool the injection nozzle during and between regeneration events.
One method of cooling an injection nozzle is described in U.S. Pat. No. 5,577,386 (the '386 patent) issued to Alary et al. on Nov. 26, 1996. Specifically, the '386 patent discloses high and low powered injectors used to inject fuel into the exhaust flow of a turbine engine. The high and low powered injectors are connected together in series to circulate fuel and coolant. Fuel is directed through an annular cavity leading to the high-powered injector, and then injected into an exhaust flow via a plurality of injection orifices. Fuel is also directed, as a coolant, through a blind bore in the high-powered injector. From the high-powered injector, the coolant is distributed by way of six separate channels to injection orifices of the low-powered injector to be injected into the exhaust flow as a fuel. In this manner, the high-powered injector, when not in use, can be cooled by the fuel flowing to and injected by the low-powered injector.
Although the injection nozzle of '386 patent may benefit somewhat from the cooling process described above, it is designed primarily for high-powered fuel injection associated with a turbine engine. As such, the injection nozzle of the '386 patent may have limited applicability for use in an internal combustion engine, and more specifically, for use in a regeneration device associated with an exhaust flow of an internal combustion engine. In particular, a regeneration device may have little use for dual injectors, or even a single high-powered injector. Moreover, even if the injectors of the '386 patent could be used with a regeneration device, it may be impractical because of the complexity and expense of the design. Furthermore, the use of fuel as a coolant may be problematic for an injector influenced by the high temperatures of an internal combustion engine's exhaust stream. These high temperatures may coke the fuel within the high-powered injector when it is not in use, causing both the coolant and the fuel passages to clog.
The regeneration device of the present disclosure solves one or more of the problems set forth above.